The temperature regulation of refrigerated containers such as, for example, refrigerated truck bodies and trailers, is managed by maintaining air flow in and out of a refrigeration unit that is often mounted to an outside surface of a front wall of such a container. In most cases, an inlet and outlet of the refrigeration unit extends into the container in order to expel cold air and receive warmer air from the trailer. Thus, warmer air may be drawn into the refrigeration unit from an inside surface of the front wall, cooled by the refrigeration unit, and then expelled from the outlet of the refrigeration unit along the container ceiling, towards a rear wall of the container.
The effective operation of a refrigerated container depends on the effective movement of cold air (expelled from an outlet of the refrigeration unit) throughout the container volume as well as the return of air (from the container volume) into an inlet of the refrigeration unit. In addition, the cooling capacity and/or energy efficiency of such containers is affected by the number of thermodynamic “short circuits” that may be present between the interior volume of the container and the environment outside the container. Such “short circuits” may result from discontinuities in container insulation and/or construction which may be caused by structural and/or mechanical elements of the container, including, but not limited to: fasteners extending through the insulated walls of the container, construction seams in the container structure, damage to the insulated walls of the container, or other discontinuities in the insulating materials of the container.
In order to protect portions of the refrigeration unit that extend into the cargo area of the container, bulkheads are often installed to ensure that cargo in the container does not shift and/or slide forward and impact the inlet and outlet portions of the refrigeration unit. Such bulkheads also serve to maintain a passage for air flow along an inside surface of the front wall of the container. Conventional bulkhead structures in refrigerated containers are attached to the container structure as an accessory structure via a number of fasteners that may, in some cases, extend through the hollow front wall structure of conventional containers, which may contain blown foam serving as an insulating material. Such conventional wall and bulkhead arrangements suffer from several disadvantages. For example, although conventional bulkhead structures may be added as aftermarket accessories that may be tailored to fit various types of containers and to provide air conduits for the refrigeration unit, conventional bulkheads also fill valuable cargo space within the container, as they are not integrated into the structure of a front wall of the container. Furthermore, conventional bulkhead structures are often fastened to the insulating wall structures of a refrigerated container using fasteners that extend through such wall structures and introduce unwanted moisture and thermodynamic “short circuits” into the insulating structure of the container. Furthermore, the front wall structures of conventional containers are often constructed from multiple structural components such as, for example, at least one front wall component and a pair of corner structural elements for connecting the front wall to the side wall of the containers. The seams introduced by conventional front wall construction, as well as the point discontinuities introduced by the fasteners attaching conventional bulkhead structure to such front wall structures, may greatly decrease the overall efficiency and cooling capabilities of a conventional refrigerated container.
Due to the thermal and other inefficiencies (such as added aerodynamic drag on refrigerated truck bodies and/or trailers) introduced by conventional front wall and bulkhead assemblies, larger, heavier, and more costly refrigeration units must often be used in order to maintain a sufficiently cool temperature within the refrigerated container to adequately transport perishable goods. In addition, in order to increase air flow to the refrigeration unit to overcome the thermal inefficiencies outlined above, some aftermarket bulkhead structures are touted as having an increased air capacity. However, as pointed out above, the installation of such aftermarket bulkhead structures (defining large-volume air ducts between the front wall and the bulkhead position), may reduce the usable cargo and/or storage space in the container, resulting in an economic loss to an operator of the container.
Although the use of conventional front wall structures and conventional aftermarket bulkheads suffer from the disadvantages outlined above, their use is still prevalent in refrigerated cargo and storage applications primarily due to availability, relative ease of assembly and adjustability, and because the use of aftermarket accessory bulkheads with convention multi-component container structures (having blown foam insulating filler) is relatively consistent and well-known. However, in light of the shortcomings of these conventional refrigerated container structures, there exists a need in the art for front wall and bulkhead structures that: minimize thermal discontinuities and/or thermodynamic “short circuits;” provide a robust and aerodynamically-efficient front wall and/or bulkhead configuration for refrigerated containers; and provide an adequate airflow to and/or through a refrigeration unit that may be operably engaged with such a wall and bulkhead structure.